Dislocations and plasticity of KTaO$_3$ perovskite modeled with a new interatomic potential

TL;DR

This paper introduces a new interatomic potential for KTaO3, enabling detailed modeling of dislocations and revealing its ductile nature and core structures through simulations validated by electron microscopy.

Contribution

A novel interatomic potential for KTaO3 is developed, allowing for accurate modeling of dislocation behavior and core structures in this ductile perovskite.

Findings

Dislocations dissociate and have well-characterized core structures.

Charge-neutral dislocations are energetically preferred.

KTaO3 is confirmed to be ductile and stiffer than SrTiO3.

Abstract

Potassium tantalate KTaO3 is a cubic, paraelectric perovskite ceramic that exhibits surprising ductility at room temperature as most recently reported. Much like strontium titanate (SrTiO3), plastic deformation is accommodated by dislocations gliding in {110} planes. In this work we propose a new interatomic potential for KTaO3, and apply it to model dislocations with <110> Burgers vector. We demonstrate that dislocations dissociate, and finely characterize their core structure and Peierls potential. Dislocations of edge character can carry a positive or negative electric charge, but we show that charge-neutral configurations are energetically more favorable. We also perform high-resolution electron microscopy to validate our simulation methodology. Comparing our results with other ductile perovskites, we confirm KTaO3 to be ductile, but stiffer than SrTiO3.